Beavers are back and thriving, with up to 600 now enjoying life along some of England's rivers, latest figures reveal.

Three centuries after the Eurasian rodent's extinction as a wild native species, 10 have been released into large outdoor, fenced enclosures since the early 2000s, all in the South-west.

These were followed by a trial reintroduction project on the River Otter, led by the Devon Wildlife Trust, from 2015.

Now Natural England has revealed populations have spread nationwide, saying all "other beavers must have been released illegally or escaped or been born in the wild".

Studies found that there are between 80 to 100 along the Otter in Devon, around 200 along the Stour in Kent, 50 along the Avon by Bristol and around 80 along the Tamar, on the Devon and Cornwall border.

And there is evidence of smaller populations on the Wye, Dorset Stour, Hampshire Avon, Taw, Exe, Little Sea at Purbeck, Dorset, Helman Tor in Cornwall, and the Brue, Somerset.

The illegal release of beavers is also a current plot on Radio 4's rural soap The Archers, as Rex and Kirsty look to set up a rewilding project. It is exposing the divide that can exist between farmers and conservationists.

Rob Stoneman, director of landscape recovery at The Wildlife Trusts, said: "The storyline is well-timed by the BBC,
as the reintroduction of this keystone species has stalled.

"While The Wildlife Trusts do not support the illegal release of any wild animal, it's vital to acknowledge the fantastic work beavers do across our river systems. Numerous scientific studies have shown they improve water quality, stabilise flows during times of drought and flood, and give a huge boost to habitats and to other wildlife."

He added: "Given the climate and nature crises, we need them back in the wild to give us a hand to resolve these challenges.

"In short, nature needs beavers but these extraordinary mammals are either living in enclosures where the benefits
to communities are limited, or they've been released illegally with no management plans in place to support farmers and landowners.

I hope Defra is listening to The Archers, too. We need government support."

A Defra spokesperson said: "This government is committed to restoring and protecting nature, and we support species reintroductions where there are clear benefits for nature, people and the environment.

"We will continue to work with Natural England on species reintroductions in England."